1. Field of the Invention
The present invention relates in general to video decoding, and more specifically to a system and method of region clustering based error concealment for recovering video packet loss in video communications.
2. Description of the Related Art
The Advanced Video Coding (AVC) standard, Part 10 of MPEG4 (Motion Picture Experts Group), otherwise known as International Telecommunication Union (ITU) H.264, include advanced compression techniques that were developed to enable transmission of video signals at a lower bit rate or storage of video signals using less storage space. The newer standard outperforms video compression techniques of prior standards in order to support higher quality streaming video at lower bit-rates and to enable internet-based video and wireless applications and the like. The standard does not define the CODEC (encoder/decoder pair) but instead defines the syntax of the encoded video bitstream along with a method of decoding the bitstream. Each video frame is subdivided and encoded at the macroblock level, where each macroblock is a 16×16 block of pixels. Each macroblock is encoded in ‘intraframe’ mode in which a prediction macroblock is formed based on reconstructed macroblocks in the current frame, or ‘interframe’ mode in which a prediction macroblock is formed based on previously reconstructed frames. The intraframe coding mode applies spatial information within the current frame in which the prediction macroblock is formed from samples in the current frame that have previously encoded, decoded and reconstructed. The interframe coding mode utilizes temporal information from previous and/or future reference frames to estimate motion to form the prediction macroblock.
It is often necessary to transmit video information over unreliable networks, such as error-prone wireless channels and the like. In an exemplary configuration, the video information is encapsulated into Real-time Transport Protocol (RTP) packets or the like in which each packet includes one or more macroblocks of a video frame. During transmission, one or more packets may be lost or corrupted due to traffic congestion or to random or burst bit errors or the like. When a packet is lost in real time, the corresponding coded macroblocks and the subsequent frames are degraded without error concealment. To further increase coding efficiency in terms of rate distortion, the newer video codec, such as according to H.264/MPEG-4 AVC, utilizes spatial-temporal correlations among macroblocks as much as possible. As a result, if a packet loss happens, the errors caused by missing information are propagated quickly without concealment. The existing video coding standards do not address error handling or concealment.
Existing solutions address recovering a lost macroblock locally by use of spatial-temporal correlations without classifying the macroblocks, which may lead to discontinuity in the boundary of the recovered macroblock and the surrounding macroblocks. The resulting video appears unpleasant or incoherent. It is desired to provide error concealment for robust video communications. Developing effective and efficient error concealment solutions for a decoder is a challenging problem.